Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933
(§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying
with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02.

Results of Operations and Financial Condition.

On May 3, 2017, Mediacom Broadband
LLC issued a press release announcing its financial results for the three months ended March 31, 2017. A copy of the press release is being furnished as Exhibit 99.1 to this report and is incorporated herein by reference.

The press release contains disclosure of operating income before depreciation and amortization (OIBDA), free cash flow, and cash
interest expense, which are not measures of performance calculated in accordance with generally accepted accounting principles (GAAP) in the United States. Reconciliations of OIBDA, free cash flow and cash interest expense to the
most directly comparable financial measures calculated and presented in accordance with GAAP are presented on Table 2 of the press release. Disclosure regarding managements reasons for presenting these non-GAAP measures is set forth on Table 4
of the press release.

Item 9.01.

Financial Statements and Exhibits.

(d)

Exhibits:

ExhibitNo.

Description

99.1

Press release issued by Mediacom Broadband LLC on May 3, 2017

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by
the undersigned hereunto duly authorized.

Revenues were $261.5 million, reflecting a 2.5% increase from the prior year period



Operating income was $62.7 million, reflecting a 0.6% decrease from the prior year period



Operating income before depreciation and amortization (OIBDA) was $99.3 million, reflecting a 0.9% increase from the prior year period



Net cash flows provided by operating activities were $81.1 million, compared to $94.4 million in the prior year period



Free cash flow of $32.0 million, compared to $32.5 million in the prior year period

About Mediacom

Mediacom Communications Corporation is the 5th largest cable operator in the U.S. serving almost 1.4 million customers in smaller markets
primarily in the Midwest and Southeast. Mediacom offers a wide array of information, communications and entertainment services to households and
businesses, including video, high-speed data, phone, and home security and automation. Through Mediacom
Business, the company provides innovative broadband solutions to commercial and public sector customers of all sizes, and sells advertising and production services under the OnMedia brand. More information about Mediacom is available at
www.mediacomcable.com.

Contacts:

Investor Relations

Media Relations

Jack P. Griffin

Thomas J. Larsen

Vice President,

Corporate Finance

Senior Vice President,

Government and Public Relations

(845) 443-2654

(845) 443-2754

*

OIBDA and free cash flow are defined under Use of Non-GAAP Financial Measures in Table 4 and are reconciled to operating income and net cash flows provided by operating activities, respectively, in Table 2.

TABLE 1*

Mediacom Broadband LLC

Selected Financial and Operating Data

(Dollars in thousands, except per unit data)

(Unaudited)

Three Months EndedMarch 31,

2017

2016

YoY% Change

Video

$

111,304

$

112,702

(1.2%)

High-speed data

89,532

80,037

11.9%

Phone

14,265

14,562

(2.0%)

Business services

36,670

34,034

7.7%

Advertising

9,737

13,883

(29.9%)

Total revenues

$

261,508

$

255,218

2.5%

Service costs

(109,062

)

(104,475

)

4.4%

SG&A expenses

(47,517

)

(46,968

)

1.2%

Management fees

(5,650

)

(5,350

)

5.6%

OIBDA (a)

$

99,279

$

98,425

0.9%

Cash interest expense (a)

(16,737

)

(19,079

)

(12.3%)

Capital expenditures

(46,037

)

(42,345

)

8.7%

Dividend to preferred members

(4,500

)

(4,500

)



Free cash flow (a)

$

32,005

$

32,501

(1.5%)

OIBDA margin (b)

38.0

%

38.6

%

March 31, 2017

March 31, 2016

YoY% Change

Video customers

461,000

479,000

(3.8%)

High-speed data (HSD) customers

652,000

621,000

5.0%

Phone customers

273,000

245,000

11.4%

Primary service units (PSUs)

1,386,000

1,345,000

3.0%

Video customer declines

(2,000

)

(1,000

)

HSD customer increases

9,000

16,000

Phone customer increases

9,000

6,000

Quarterly PSU increases

16,000

21,000

Customer relationships (c)

757,000

740,000

2.3%

Average total monthly revenue per:

PSU (d)

$

63.26

$

63.75

(0.8%)

Customer relationship (e)

$

115.38

$

115.59

(0.2%)

March 31, 2017

March 31, 2016

Bank credit facility

$

1,091,000

$

1,280,000

5 1⁄2%
senior notes due 2021

200,000

200,000

6 3⁄8%
senior notes due 2023

300,000

300,000

Total debt (f)

$

1,591,000

$

1,780,000

Total leverage ratio (g)

4.01x

4.52x

Interest coverage ratio (h)

5.93x

5.16x

*

See Table 2 for reconciliations of OIBDA to operating income, cash interest expense to interest expense, net, and free cash flow to net cash flows from operating activities. See Table 3 for details of capital
expenditures. See footnotes on Page 4, which contain important disclosures regarding the definitions used for selected unaudited financial and operating data.

Page 2 of 4

TABLE 2

Mediacom Broadband LLC

Reconciliation of Non-GAAP Measures

(Dollars in thousands)

(Unaudited)

Three Months EndedMarch 31,

2017

2016

Free cash flow

$

32,005

$

32,501

Capital expenditures

46,037

42,345

Dividend to preferred members

4,500

4,500

Other expense, net

(318

)

(469

)

Changes in assets and liabilities, net

(1,153

)

15,526

Net cash flows provided by operating activities

$

81,071

$

94,403

OIBDA

$

99,279

$

98,425

Depreciation and amortization

(36,579

)

(35,328

)

Operating income

$

62,700

$

63,097

Cash interest expense

$

16,737

$

19,079

Amortization of deferred financing costs

1,056

1,588

Interest expense, net

$

17,793

$

20,667

TABLE 3

Mediacom Broadband LLC

Capital Expenditures

(Dollars in thousands)

(Unaudited)

Three Months EndedMarch 31,

2017

2016

Customer premise equipment

$

20,036

$

19,347

Enterprise networks

2,096

1,959

Scalable infrastructure

10,998

9,547

Line extensions

2,582

2,552

Upgrade / rebuild

7,043

5,810

Support capital

3,282

3,130

Total capital expenditures

$

46,037

$

42,345

Page 3 of 4

TABLE 4

Use of Non-GAAP Financial Measures

OIBDA, cash interest expense and free cash flow are not financial measures calculated in accordance with generally
accepted accounting principles (GAAP) in the United States. We define OIBDA as operating income before depreciation and amortization. We define cash interest expense as interest expense, net, less amortization of deferred financing
costs. We define free cash flow as OIBDA less capital expenditures, cash interest expense and dividends to preferred members.

OIBDA is one of the primary
measures used by management to evaluate our performance and to forecast future results. We believe OIBDA is useful for investors because it enables them to assess our performance in a manner similar to the methods used by management, and provide
measures that can be used to analyze our value and evaluate our performance compared to other companies in the cable industry. A limitation of OIBDA, however, is that it excludes depreciation and amortization, which represents the periodic costs of
certain capitalized tangible and intangible assets used in generating revenues in our business. Management utilizes a separate process to budget, measure and evaluate capital expenditures. OIBDA might not be comparable to similarly titled measures
used by other companies, which may have different depreciation and amortization policies, and are key components in our covenant calculations.

Free cash
flow is used by management to evaluate our ability to repay debt and facilitate the growth of our business with internally generated funds. A limitation of free cash flow, however, is that it may be affected by the timing of our capital spending. We
believe free cash flow is useful for investors as it provides an additional measure that can be used to analyze our value and evaluate our performance compared to other companies in the cable industry. Free cash flow may not be comparable to
similarly titled measures reported by other companies.

OIBDA and free cash flow should not be regarded as alternatives to operating income or net income
as indicators of operating performance, or to the statement of cash flows as measures of liquidity, nor should they be considered in isolation or as substitutes for financial measures prepared in accordance with GAAP. We believe that operating
income is the most directly comparable GAAP financial measure to OIBDA and that net cash flows provided by operating activities is the most directly comparable GAAP financial measure to free cash flow.

Cash interest expense excludes the amortization of financing costs which were paid upon the financing of the relevant debt. We believe cash interest expense
is useful for investors because it enables them to assess our cost of debt for the current period without including the amortization of financing costs that were previously paid. We believe interest expense, net, is the most directly comparable GAAP
financial measure to cash interest expense.

For reconciliations of OIBDA, cash interest expense and free cash flow to their most directly comparable GAAP
financial measures, see Table 2.

FOOTNOTES:

(a)

See Table 2 for information about our use of Non-GAAP financial measures.

(b)

Represents OIBDA as a percentage of total revenues.

(c)

Represents the total number of customers that receive at least one service, without regard to which service(s) customers purchase.

(d)

Represents average total monthly revenues for the quarter divided by average PSUs for such quarter.

(e)

Represents average total monthly revenues for the quarter divided by average customer relationships for such quarter.

(f)

Total debt excludes the effect of deferred financing costs, net.

(g)

Represents total debt at quarter end divided by annualized OIBDA for the quarter.